1. Field of the Invention
The present invention relates to a circuit and method for searching a track on a CD. More specifically, the present invention relates to an IC track search circuit for processing and controlling signals in a CD (compact disc) player, and a track search method for rapidly finding a cue of a piece of music.
2. Description of the Prior Art
In the data format of a CD, subcodes are formed in respective frames. A subcode Q within the subcodes includes the number of pieces of music, indexes and time information. Therefore finding a cue of a piece of music involves reading and utilizing the subcode Q, and moving or feeding an optical pick-up toward a target position.
Conventionally, the process of finding a cue of music (search) and moving the optical pick-up to a set target position encompasses calculating the target time to the target position to evaluate the time difference between the time represented by the time information of the subcode Q which has been presently read and the target time, and evaluating the amount of movement, i.e. the moving amount of the optical pick-up so as to make the time difference of approximately zero. Then, the optical pick-up is moved by using the moving amount as a control target. More specifically, setting a time period equal to an evaluated moving amount in a timer and moving the optical pick-up until the timer counts the time period set in the timer allows the optical pick-up to catch or capture the target position.
Such a search method is disclosed in Japanese Patent Application Laid-open No. 83272/1985.
In the above described method, the track number, a cue of index, and etc. are directed to a control device such as a microcomputer by means of key operation, but it is not easy to calculate and evaluate the time period to the target position in accordance with such information because of the size of the necessary program. Another disadvantage, arises because the calculation for evaluating the time difference between the time information of the target position and the time information of the subcode Q which has been presently read and for further evaluating a moving time period of the optical pick-up based upon the time difference is quite complex. Thus as the length of the program for such calculation becomes longer the load a the microcomputer increases.